Wire bending machine



Feb. 3, 970 E. G. OTT

WIRE BENDING MACHINE Filed June 16, 1967 14 Sheets-Sheet l Nix INVENTORFeb. 3, E. G OTT WIRE BENDING MACHINE INVENT OR BY im? Feb. 3, 1970 E.G. OTT

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Feb. 3, 1970 E. G. OTT

YWIRE BENDING MACHINE TTORNEYS Feb. 3, 1970 E. G. OTT 3,493,016

wRE BENDING MACHINE Filed June 16, 1967 14 sheets-Sheet e ENT OR MMMFeb. 3, 1970 E. G. oT'r WIRE BENDING MACHINE 14 Sheets-Sheet '7 FiledJune 16. 1967 INVENTOR O fpm/1 055 @uw fnw ATTORNEYS Feb. 3, 1970 E. G.OTT 3,493,016

WIRE BENDING MACHINE Filed June 16, 1967 1.4 Sheets-Sheet 8 INVENT OR/zsi i BY M M b ATTORNEYS Feb.' 3, 1970 E. G. 01'1 3,493,016

WIRE BENDING MACHINE Filed June 1.6, 1967 14 Sheets-Sheet 9 SOZ-I INVENTOR [msi 0% 1- 4122* 2- l Aw Feb. 3, 1976 E. G OTT 3,493,016

WIRE BENDING MACHINE INVENTOR E. G. OTT

WIRE BENDING MACHINE Feb. 3, 1970 INV ENT OR ATTORNEYS m c m l Ml l Feb.3, 1970 E. G.- OTT 4 WIRE BENDING MACHINE 14 sheets-sheet 12 INVENTORfp/73m @ai M @n/Mm Y B 95m@ Il l QQKQS QN l wmv w @Awww SQ mw: nl' e w J,w u.

Feb. 3, 1970 E. G. on'

WIRE BENDING MACHINE 14 Sheets-Sheet l5 Filed June 16, 1967 INVENTOR'f/s'i J BY wwf/WM Feb. 3, 1970 E. G. OTT

WIRE BENDING MACHINE 14 Sheets-Sheet 14 Filed June 16, 1967 INVENTOR@fnv/MAQ??? BY d@ United States Patent O U.S. Cl. 140-71 36 ClaimsABSTRACT OF THE DISCLOSURE This disclosure contains drawings and adescription of an improved machine for bending linear stock material,particularly wire to form undulating or zig-bag springs of the type usedin furniture or automotive seat cushions. The machine features arotatably mounted bending head disposed on the axis of the material tobe Ibent so that the rotational or angular position of the head on theaxis will determine the radial plane in which a bend is made uponactuation of the head. Stock material feed, as well as head angleposition and cycle control are synchronized by the relation of thesefunctions to a programming carn template so that the ultimateconfiguration formed, such as a spring for example, will be determinedby the particular template used. To this end, the template isinterchangeable with other templates. The machine includes further anadjustable bend stop arrangement so that the angle of bend in a singlebending place may be predetermined and incorporated in a programmedbendin-g cycle.

BACKGROUND OF THE INVENTION The present invention relates to a machinefor bending linear stock material such as wire, rods, tubes and thelike. More particularly, it concerns an improved machine for formingautomatically undulating or zig-zag springs of the type used infurniture and automotive seat constructions.

In a copending application Ser. No. 456,981, filed May 19, 1965 by thepresent inventor, now U. S. Patent No. 3,393,714, there is disclosed awire bending machine generally characterized as having a carriagesupported, rotatable bending head movable along a straight length ofspring wire stock under appropriate controls to form substantially anyshape of zig-zag spring in one continuous operation. The bending head isrotatable about the axis of the spring wire stock, and in the preferredembodiment, is moved relative to the wire by advancing the carriagealong ways spaced sufficiently from each other and the head to enablethe formation of a spring of standard length. The carriage position onthe ways, therefore, establishes the point on the wire where a singleplane bend is to be made. The angular position of the head about theaxis of the wire, on the other hand, establishes the radial direction orplane in which the bend is made upon actuation of the head. Both thecarriage position along the length of the wire and the angular positionof the head about the axis of the wire are controlled by aninterchangeable programming device, such as replaceable cam track or thelike, adapted to be followed by a control element on the carriage orhead. The various operating components of the machine are driven byfluid motors operated by an electrical control system.

Machines of the type to which this and the aforesaid copendingapplication relate have been found extremely effective in practice bothfrom the standpoint of reducing the time required to adapt the machineto the formation of different shaped springs and also from thestandpoint of producing springs of higher quality than more conventionalspring forming machines. In the latter respect, the improved springcharacteristics are believed to be as a result of enabling each bend inthe wire to be formed in a single bending step from a reasonablystraight wire. This is in contrast to previously conventional machineswhich not only required the spring stock to be bent entirely within asingle plane and then again bent out of the plane at various points, butalso, they required extremely straight wire stock to start with. As aresult of the numerous straightening and bending operations that wererequired to be performed on the wire stock, the wire stock becamecold-worked, thereby losing a substantial part of its inherent spring orresilient properties.

SUMMARY OF THE INVENTION In accordance with the present invention, thedesirable attributes of the machine disclosed in copending applicationSer. No. 456,981 led May 19, 1956, are retained while at the same timeproviding various improvements and/or additional desirable features.Generally, a significant reduction in size of the machine is achieved bymounting the rotatable bending head in a fixed position projecting fromthe machine frame or support in cantilever fashion so that no provisionneed be made for ermitting free movement of the formed spring or bentwire about the rotatable axis of the head. The spacing between variousbends made on the Wire is regulated by a wire feed mechanismsynchronized with the bending head angle by a rotatably driven camtemplate. The template is interchangeable with other similar butdifferently shaped templates and also carries a plurality of controllinglimit switch actuating devices so that the complete bending cycle may bealtered as desired merely by using the appropriate template. The machineof the present invention further includes an improved bending headtogether with a mechanism offering added facility for determining theangle through which the wire is to be bent in a given bending plane.

Among the objects of the present invention are therefore; the provisionof an improved wire bending machine capable of being actuatedautomatically to produce a series of bends in a generally linear stockmaterial at precisely spaced points and in any desired radial bendingplane that may be required to form a particular configuration; theprovision of a bending machine of the type referred to which is compactand requires a minimum of floor space; the provision of a wire bendingmachine having an improved bending head which enables the making of abend through any given angle with a minimum of cold working of the wire;the provision of a wire bending machine of the type referred to whichprovides enhanced facility for controlling both the angular position ofthe bending head within extremely close tolerances and the angle of asingle plane bend; and the provision of an improved control mechanismfor a wire bending machine of the type referred to above.

Other objects and further scope of applicability of the presentinvention will become apparent from the description to follow belowtaken in conjunction with the accompanying drawings in which likereference numerals designate like parts.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. l is a fragmentary sideelevationof a bending machine in accordance with this invention;

FIG. 2 is an enlarged fragmentary plan view as seen from line 2-2 ofFIG. l;

FIGS. 3a and3b are enlarged fragmentary cross-sectional views takenrespectively on lines 3a-3a and 3b-3b of FIG. 2;

FIG. 4 is an enlarged fragmentary plan view showing various componentsof the bending head in different relative operative positions from thatshown in FIG. 2;

FIG. 5 is an enlarged fragmentary cross-section taken 1 line 5 5 of FIG.2;

FIG. 6 is a cross-section taken on line 6 6 of FIG. 5; FIG. 7 is anenlarged fragmentary cross-section taken tline 7 7 of FIG. 3a;

FIG. 8 is an enlarged cross-section taken on line 8 8 FIG. 3a;

FIG. 9 is an enlarged cross-section taken on line 9 9 EFIG. 3a;

FIG. 10 is an exploded view showing the components E a bending quillstop in accordance with one emboditent of this invention;

FIG. 11 is an enlarged cross-section taken on line 11- 1 of FIG. 3b;

FIG. l2 is an anlarged cross-section taken on line 12- Z of FIG. 3b;

FIG. 13 is an enlarged fragmentary end elevation as :en from line 13 13of FIG. 3b;

FIG. 14 is an enlarged fragmentary cross-section taken n line 14 14 ofFIG. 1;

FIG. 15 is a schematic diagram illustrating a hydraulic rcuit foroperating the machine illustrated in FIGS. d14;

FIG. 16 is a circuit diagram used with the hydraulic ircuit of FIG. 15;

FIG. 17 is a fragmentary perspective view of a zig-zag oring formed bythe machine of the present invention;

FIGS. 18-20 are end elevations of the wire bending ead of this inventionduring different phases of forming 1e spring illustrated in FIG. 17;

FIGS. 21-23 are fragmentary cross-sectional views 'irough the wirebending head at various forming phases f the Spring shown in FIG. 17;

FIG. 24 is a fragmentary side elevation showing the rogramming controlfor an alternative embodiment of nis invention;

FIG. 25 is a fragmentary plan view of the alternative mbodiment; and

FIG. 26 is a fragmentary cross-section taken on line .6 26 of FIG. 25.

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the presentinvention is illustrated n FIGS. 1-16 of the drawings. As shown in thesefigures, tnd particularly in FIGS. 1 and 2, the bending machine )f thisinvention generally includes a supporting frame l0 having an elongatedhorizontal bed 12 on which larious working components of the machine aresupnorted. These components include a bending and cutoff read assembly14, a head driving and support housing l6, a feed mechanism 18 and awire straightening device l0. A rotatable programming control cam,designated Jy the reference numeral 22, is housed within the supvsortingframe 10. Also, a housing containing various con- ;rol elements andpower generating devices, such as a nydraulic fluid pump, are containedin a housing 24 supported under the bed 12.

As shown most clearly in FIGS. 3a and 5-7, the bendlng and cutoff head14 includes an elongated wire guide nember 24 having a circular boss 26secured by set screws Z8 in a counter bore formed on the end of anelongated ubular spindle 30 to be described in more detail below. Thefront or projecting end of the guide member 24 terminates in a roundedor cylindrical bending anvil 32 which merges tangentially with alongitudinal wire guide bore 34 of a diameter to accommodate the largestiiameter of a wire W or other linear stock material to be bent. A radialset screw 36 in the guide member 24 provides a measure .of adjustment inthe effective diameter 3f the guiding bore 34 to insure that the wire Wwill be held against th@ surface of the guide bore adjacent the anvil32. The guide bore 36 opens to an enlarged counter bere 35 which, asshQWti in FIG, 5, forms an extension Q f the inside diameter of thetubular spindle 30. A bending die in the form of a grooved roller 40 isjournaled in a pair of bell crank arms or -plates 42 mounted for pivotalmovement about a pin 44 extending centrally through the anvil 32. Thusit will be appreciated that the wire W, fed between the roller die 40and the anvil 32, will be bent about the anvil upon movement of the die40 in a circular path about the axis of the pin 44 which coincides withthe axis of the anvil 32. To effect this movement, a pair of actuatingpins or studs 46 projecting outwardly from the crank plates 42 on anaxis displaced from the axis of the pin 44 are received in verticallydisposed cam slots 48 formed in a reciprocal bending die actuatingmember 50 slidably mounted on the spindle 30. By reference to FIG. 3a,it will be noted that the studs 46 are constrained by the slots 48 to anarcuate path of less than 90 to either side of a transverse planeIpassing through the axes of the anvil 32 and die 40 'when the latter isin its starting or retracted position. This arrangement avoids adead-center position of the crank plates 42.

To provide for cutting the wire W, a cutoff pin 52 having a wireaperture 54 is slidably mounted in a transverse bore provided in theguide member 24. As shown in FIG. 5, the pin 52 is biased outwardly byspring 55 to a position of where the aperture 54 generally aligns withthe wire guide aperture 34 in the guide member 24. A cutting die 56 ismounted in the guide member 24 so that movement of the pins 52 inwardly,will effect a shearing action between the edge of the aperture 54 andthe cutting die 56 to sever the wire W. To move the pin 52 in thismanner to cut the wire, the head of the pin underlies one end of a leverarm 58 pivotally supported from the guide member 24 by a pin 60. Asshown most clearly in FIG. 4, the arm 58 is bifurcated at its rearwardend to receive a pair of spaced cam follower rollers 62 and 64. As shownin FIG. 3a, the rollers 62 and 64 lie on opposite sides of an inclinedcramming finger 166 projecting from a cutoff quill 68 slidably androtatably mounted on the head spindle 30. The quill 68 is formed with acircular fiange 70 to be engaged on opposite sides by a pair of rollers72 mounted on a cutoff die actuating rod 74. The rod 74, as shown inFIG. 2 of the drawings, is connected to the piston of a piston-cylinderhydraulic motor 76 mounted on the housing 16. Thus it will beappreciated that actuation of the motor 76 to advance the rod 74, andthus the quill 68 forwardly, will cause the roller 62 to ride up on thefront cam surface of the finger 66, in turn causing the lever arm 58 tomove the cutoff pin relative to the guide 56 and sever the wire in themanner described. Correspondingly, rearward movement of the quill 68 bythe motor 76 will cause the roller 64 to ride downwardly on the rearsurface of the camming finger 66 to move the lever ar-m into a neutralposition. Because of the spring 55 biasing the pin 52 into engagementwith the lever arm 58, the cutoff pin S2 will be properly aligned withthe guide aperture 34 in the head guide member 24.

As shown most clearly in FIG. 2 of the drawings, the bending dieactuating slide 50 is connected by a pair of rods 78 to the front end ofa bending quill 80 slidably and rotatably carried on the head spindle30. Because the bending quill 80 is situated behind the cutting quill68, the flange 70 in the cutoff quill is apertured to accommodate therods 78. The bending quill 80 also has a circular fiange 82 forengagement by a pair of rollers 84 mounted on a bending quill actuatingrod 86 operatively connected to a hydraulic bending motor 88 mounted onthe housing 16. Thus it will be seen that when the motor 88 is actuatedto advance the rod 86 toward the head 14, the bending die actuatingslide 50 will move forward to carry the roller die 40 through thecircular or arcuate path described above and as shown in FIG. 3a of thedrawings.

It will be appreciated that the bending head organization described thusfar will operate to bend the wire W in a single plane. To change theplane of the bend, however, it is necessary that the pivotal plane ofthe bending die 40 be adjustable angularly about the axis of the wire W.To accommodate this angular or rotatable movement of the head 14relative to the wire W the spindle 30, on which the head is mounted, isrotatably supported in the housing 16 on spaced bearings 90 and 92 asshown most clearly in FIG. 3b. Also, it will be noted that the bearing92 is a combined radial and thrust bearing t0 constrain the spindle 30,and thus the head 14, in a fixed axial position relative to therespective cutoff and bending quills 68 and 80. Also, it will be notedthat the rear end of the tubular spindle 30 is keyed to a hollow shaftextension 94 journaled in the rear wall 96 of the housing 16 toestablish a continuous straight wire feed passage 97 from the shaftextension 94 to the head 14.

The manner in which the angular position of the spindle 30, and thus ofthe head 14, is controlled in the present embodiment, may be understoodby reference to FIGS. 1, 3b, 11 and 14 of the drawings. As shown in FIG.3b, the shaft extension 94 is formed having a gear 98 on its front endin mesh with a double pinion gear 100 journaled on a hollow trunnionshaft 102 extending between the rear wall 96 and the front wall portionof a sealed gear chamber 104 in the housing 16. As shown in FIG. 11, avertically disposed rack 106 slidably mounted within a guide tube 108secured to the housing 16 is in mesh with the double pinion gear 100.The lower end of the rack 106 carries a earn follower roller 110, whichin turn, engages a peripheral cam pattern 112 on the programming controltemplate 22. To insure contact of the follower 110 with the cam 22, andalso to minimize back lash through the gears 98 and 100 and the rack106, a hydraulic pressure bias is imposed on the shaft extension 94 in adirection tending to move the cam follower 110 into engagement with cam22. This pressure bias is developed by a motor 114 having a piston (notshown) connected by a rod 116 to a horizontally disposed rack 118movable in slide bearings 120 on opposite sides of the gear chamber 104.The rack engages a pinion 122 formed integrally on the shaft extension94. Thus, and as shown in FIG. 11 of the drawings, a biasing forceexerted by the motor 114 to the right of FIG. 11 will exert a clockwisebias on the gear 98, a counter clockwise bias on the double pinion gear100, and a downward bias on the rack 106 and cam follower 110.

Although the operation of the bending head to form a zig-zag spring of aconfiguration shown in FIG. 17 will be described in more detail below,it might be noted at this point that the length of the arc or anglethrough which the wire bending roller die 40 moves in its path about thecylindrical anvil 32 will determine the angle to which the wire is bentin the single bending plane. For example, to make a 90 bend in the wireW, the roller will move approximately through a 90 arc, beginning fromits starting position on a transverse or radial line normal to the wireW. Correspondingly, movement of the die through less than 90 will resultin a smaller bend angle in the wire (i.e., an underbend) and longer arcsof the die will produce bend angles greater than 90 (i.e., an overbend).

In accordance with the embodiment of the present invention shown inFIGS. l-l6, the angle through which the bending die 40 travels isrendered adjustable by a multiposition stop assembly engageable by thebending quill flange 82 and generally designated in the drawings by thereference numeral 124. A complete understanding of the stop mechanism124 may be had by reference to FIGS. 1, 3a, 3b, 8-10, 12 and 13. Asshown in FIGS. 3a, 3b and 8 of the drawings, a rotatable stop supportingdisc 126 is fixed at the end of a shaft 128 journaled in a bracket 130suitably supported on the front of the housing 16 under the bendingquill 80. The shaft 128 is keyed at its rear end to a drive shaft 132which extends through the hollow trunnion 102 in the sealed gear chamber104 and which is keyed in turn at its rear end, to a pinion 134contained within a motor housing 136 secured to the rear wall 96 of thehousing 16. As shown in FIG. l2, the pinion 134 meshes with a rack 138having piston heads 140 at opposite ends thereof slidable in a hydrauliccylinder 142 defined by the motor housing 136. The rack is biased bysprings 144 to a central position and operates between a pair of fixedstops 146 secured at each end in the cylinder 142. Hydraulic lines 148are provided to introduce hydraulic uid into or out of the cylinder 142on the sides of the respective pistons 140, to move the rack 138 fromits central position, as shown in FIG. 12, to a left or right positionas established by the stops 146.

The disc 126 has three angularly displaced, internally threaded axialapertures formed therein to receive externally threaded quill stops 150,152 and 154, respectively (FIG. 8). In this embodiment, the central stop152 constitutes a bend stop whereas the stops 150 and 154 to either sideof the central stop establish respectively, an underbend stop and anoverbend stop. The stops 150, 152 and 154 are spaced angularly on thedisc 126 so that only one stop at a time is positioned in front of thebending quill ange 82 where the disc 126 is rotated to one of threepositions established by the rack 138 (FIG. 12); i.e., in its centralposition or against one of the two side stops 146. Thus it will beappreciated that the maximum forward position of the bending quill 80and of the bending head slide 50, as the bending motor 88 is actuated toadvance the quill 80, will be established by engagement of the flange 82with one of the stops 150, 152 or 154 that is adjusted to the verticalposition as shown in FIG. 8. Correspondingly, the arc through which thebending die roller 40 is moved will also be determined by the maximumforward position of the slots 48 in the slide 50.

rthe construction of one form of the programming control cam 22 may beunderstood most clearly by reference to FIGS. 1 and 14 of the drawings.As shown, the cam 22 is in the form of a generally circular templatecarrying the peripheral cam pattern 112 for engagement by the followeras described above and being removably mounted on a flanged hub 156 bysuitable means such as screw bolts 158. The hub 156, in turn, isremovably mounted `on an axle 160 journaled in spaced bearings 162 and164 carried by the frame 10. To enclose the cam, the front portion ofthe frame supports a hinged door 166 to facilitate access to the cam 22as well as its removal by first removing the hub 156 and then removingthe cam 22 from the hub 156. The axle 160 is splined or otherwisenonrotatably fixed to the shaft 168 of a rotary hydraulic motor 170.Also keyed on the axle 160 is a sprocket 172 coupled to a drive roller174 in the wire feed mechanism 18 by 4a drive chain 176 (FIGURE l). Itwill be noted further at this point that the wire feed mechanismincludes a pressure roll 178 carried on a pivotal arm 180 connected to ahydraulic piston-cylinder motor 182. Hence rotation of the drive roll insynchronism with the cam 22 by the motor 170 will operate to advance thewire W toward the bending head 14 so long as the pressure roll 178 isurged against the drive roll 174 by the motor 182. Conversely,retraction of the pressure roll 178 by the motor 182 will terminate wirefeed.

The cam template 22 also carries a plurality of timing pins 184projecting from the rear face thereof as shown in FIG. 14, and arrangedin circles of varying radii concentric with the template drive axle 160.In the embodiment above described, five limit switches LS1-LS5 aresupported on a radial arm 186, in turn carried by a bracket 188 from theframe 10. As will become apparent from the description of the circuitdiagrams of FIGS. 15 and 16 below, the limit switches LS1-L55 effect theinitial control functions by which the various hydraulic motors 76, 88,142, and 182 are actuated. It will be readily appreciated that thelocation of the pins 184 on the rear face template 22 will determine thepoint in a ending cycle at which these various functions are pertrmed.

In addition to the limit switches LS1-L85, other limit vitches areprovided, principally for the purpose of inlring that a particularmachine condition is in readiness r a subsequent machine operation.Specifically, a limit vitch LS6 mounted on the housing 16 as shown inFIG.

cooperates with a camming collar 190 fixed on the ending head actuatingrod 86 to signal or indicate the :tracted position of the bending head.A pair of similar mit switches LS8 and L89, mounted on the housing 16 ndas shown in FIGS. 1 and 2 of the drawings, signal espectively theretracted and extended position of the utting head quill 68 bycooperation with a pair of camiing collars 192 and 193 on the rod 74.

The extended position of the bending head thus of the ending head quill80 is signaled by tripping a limit witch LS7 shown in FIG. 3a of thedrawings. To ena-ble 1e switch LS7 to be tripped when the bending headquill i moved to its extended position, each of the stops 150, 52 and154 is formed with a longitudinal bore 194 and n enlarged counter bore196 to receive a flanged plunger 98. As shown most clearly in FIGS. 3aand l0 of the rawings, the plunger 198 is biased to a position such hatthe flange thereon is at the base of the counter bore 96 by acompression spring 200 abutting between the lange on the plunger 198 andan externally threaded col- 1r 202 received within an internallythreaded portion of he counter bore 196. A bolt-like member 204 having alead 206 is threadably fixed to the plunger 19S to comlete the assemblyof each of the stop members 150, 152 .nd 154. A rocker arm 208 having asemi-circular upper lortion 210 is pivotally supported on a bracketportion i12 formed as the extension of the bracket 130. The low- =r legof Ithe arm 208 abuts against a plunger 214 spring iased forwardly by aspring 216 and carrying a switch `ripping head 218 at its rearward end.Thus it will be seen hat when the bending head quill flange 82 isadvanced igainst either one of the stops 150, 152 or 154, the cor-'esponding plunger 198 will be advanced to rock the arm 508 in a counterclockwise direction, as shown in FIG. a, to move the striking head 218against the limit switch LS'7. In this manner, the limit switch LS7 willbe tripped ipon the bending head reaching its extended positionregardless of whether that position has been preselected for t normalbend, an overbend, or an underbend.

To signal the movement of either the underbend stop [50 or the overbendstop 154 to an operative position in front of the quill ange 70, a pairof limit switches LS10 and LS11 are provided as shown in FIG. 13 of thedrawings. A pair of set screws 220 and 222 are mounted on a bracketkeyed to the rear end of the shaft 132. Hence, when the overbend stop154 is positioned in front of the bending head quill ange 70, the setscrew 222 will trip the limit switch LS10 whereas movement of theunderbend stop will be signaled by the set screw 222 to tripping thelimit switch LS11. A further limit switch LS12 is positioned ahead ofthe wire feed engaging plunger or motor 182 as shown in FIG. l of thedrawings.

The manner in which the various hydraulic motors 76, 88, 142, 170 and182 are operated through a pre-established bending cycle under thecontrol of the timing pins 184 and the limit switches LS1 to LSS may beunderstood by reference to FIGS. 15 and 16 of the drawings. Each ofthese motors is illustrated schematically in FIG. 15

together with the electric and hydraulic circuitry employed to controltheir actuation. Hence, hydraulic iiuid is pumped from a tank or sump224 Iby a pump 226 into a supply line 228, ultimately to be returned tothe sump 224 through a return line 230. The circulation of hydraulicfluid through the respective hydraulic motors illustrated is under thecontrol of solenoid actuated, spring return valves, each of which isshown in its normal ilow controlling position in FIG. 15. Hence, thetemplate drive motor 17() is controlled by a normally closed, one-wayvalve 232 arranged to be moved to its pen position to admit fluid to andfrom the drive motor upon energization of its associated solenoid SOL-1.Hence, it will be appreciated that the template drive motor 170 will beoperative only when the solenoid SOL-1 is energized by closure of arelay switch S3e.

The cutting head actuating motor 76 is controlled by a two-way valve 234normally positioned to admit hydraulic uid from the line 228 in a mannerto retract the piston thereof or position the cutting head in itsrearward position. Energization of the solenoid SOL-2 by closure of arelay switch SSC will reverse the direction of flow through the motor 76to advance the piston of the motor 76 and thus the cutting head. Thebending motor 88 is similarly controlled by a Valve 236 and solenoid|SOL-3 under the control of a relay switch 88a. Likewise, the wire feedengaging roller actuating motor 182 is controlled by a two-way valve 238under the control of a solenoid SOL*6 depending upon the position of arelay switch S14b.

The bending head stop positioning motor 142 which, as described above,includes a two-way piston 138 spring biased to its central or neutralposition, is operated under the control of a three-Way valve 240. In itsneutral position, the valve 240 equalizes fluid pressure on oppositesides of the piston 138. When, however, the solenoid SOL-4 is actuatedby closure of the relay switch S125, the supply line 228 is connected tothe left hand chamber to advance the piston 138 to the right to effectan underbend. Conversely, if the solenoid SOL-5 is energized, the valve240 is positioned to connect the supply line 228 with the right handchamber and move the piston 138 to the left to effect an overbend.

The biasing lmotor 114 is connected between the supply line 228 and thereturn line 230 at all times under the control of a pressure regulator242.

It should be noted at this point that each of the motor positionindicating limit switches LS6 to LS12 are normally open switches. Hence,and as depicted schematically to FIG. l5, the normally retractedposition of both the cutting head motor 76 and the bending head motor818 will operate to close the switches LS8 and LS6, resp-ectively. Eachof the other limit switches referred to will remain in their openposition when the pump 226 is operated to supply fluid under pressure tothe line 228.

In the circuit diagram of FIG. 16, fourteen relay coils designatedR1-R14 respectively, will be energized by the completion of a circuitthrough the respective coils from the lines A and B. The switch contactsfor each relay are designated by a prex letter S followed by a numeralcorresponding to the numeral sux `designating the relay coils. A smallletter suix in the designation of each relay switch serves to identifythe individual switches actuated by energization of any of the relaycoils lll-R14, respectively. Normally open relay switch contacts areillustrated assuch in FIG. 16 whereas normally closed relay switches arealso so indi-cated by the illustration of a closed relay switch. Itmight also be noted at this point that energization of certain of therelays will directly complete the circuits of the respective valveactuating solenoids illustrated in FIG. 15 For example, when the relayR3 is energized the switch S3e is closed to energize the solenoid SOL-1;energization of the relay R5 closes the switch SSc` to energize thesolenoid SOL-2; energization of the relay R8 closes the switch S'Sa toenergize the solenoid SOL-3; energization of the relay R12 closes theswitch S12b to energize the solenoid SOL-4; energization of the relayR13 lcloses the switch S1311 to energize the solenoid SOL-5; andenergization of the relay coil R14 closes the switch S14b to energizethe solenoid SOL-6. In addition to the relay switches S1-S14 in FIG. 16,the limit switches LS1-LS12 are shown in the position they assume whenthe machine is at rest with the hydraulic pump 226 in operation. Inother words, all of the limit switches are open with the exception ofLS6 and LS8,

which are operated by the bending head and cutting head, respectively.The limit switches LS1 and LS2 which are two-way switches biased to anormal position as shown. In addition, four push buttons are illustratedin the circuit and designated by the letter prefixes PB. These pushybuttons are manually operated switches also biased to the normalposition shown.

lt is apparent, therefore, that with the hydraulic pump 226 inoperation, the position of the several switches illustrated in FIGS. 22and 23 will be as shown in the drawings. To start a cycle of operation,the push button PBI is closed to complete a circuit through the relaycoil R1, the switch 84a having been closed by the energized character ofthe relay coil R4. When the push button PB1 is released, the circuitthrough the relay R1 remains due to a holding circuit through the switchSla. The energization of the relay coil R1 also closes the switch Slb toenergize the relay coil R2 and its associated holding circuit throughthe switch S2a.

At this point, it will be noted that the two-way limit switches LS1 andLS2 serve to complete the circuit through the relay coils R6 and R9,respectively, thereby closing the relay switches 86a and 59a. Since therelay coil R2 is energized also at this time, a circuit will becompleted through the relay coil R3 by switches S2c, S911, 56a, S14a,Silla and LSS, the latter limit switch being closed by the retractedposition of the cutting head. Energizing the relay coil R3, as abovementioned, also closes the switch S3e (FIG. 15) to actuate the templatedrive motor 170. The template 22 will be rotatably driven by the motor170 until the limit switch LS2 is tripped by one of the pins 184. Itwill be remembered also at this point that since the wire drive motor182 is advanced by hydraulic pressure to hold the pressure roller 178 inengagement with the drive roller 174, wire feed will occursimultaneously with rotation of the template 22.

When the limit switch LS2 is tripped, the relay coil R5 is energizedthrough S4b, LS2, S7b, and S3a. Immediately before energization of therelay R5, however, the relay R6 is de-energized, thereby permitting theswitch S6a to open and de-energize the relay R3 to terminate operationof the template drive motor 170. When the relay R5 is energized, theswitch SSC closes to reverse the position of the solenoid actuated valve234 and advance the cutting head to its extended position therebypermitting the limit switch LSS to open and bring about closure of thelimit switch LS9. Closure of the limit switch LS9 energizes the relaycoil R7 and its holding circuit through the switch S7c. This also closesthe switch S7rz to enable the circuit for the relay coil R3 for closurewhen the cutting head retracts to again close the limit switch LS8.Also, it will be noted that as soon as the limit switch L89 had beenclosed by the cutting head reaching its extended position, the relaycoil R5 was deenergized by opening of the switch S7b, therebydeenergizing by opening of the switch S7b, thereby de-energizing thesolenoid SOL-2 to return the valve 234 to its original position underits spring bias. This function brings about retraction of the cuttinghead hydraulically, ultimately to close the limit switch LS8 andre-energize the relay coil R3 to initiate template rotation by actuatingthe template drive motor 170. Also rotation of the template will restorethe limit switch LS2 to its original position.

The template will continue to rotate until the limit switch LS1 istripped to de-energize the relay coil R9 and thus de-energize the relaycoil R3 to terminate template drive by opening the switch S9a. Also, atthis point, the relay switch S9b is restored to its normally closedposition. Then, the circuit through the relay coil R8 is completedthrough LS1, S12b, S13b, S10b and S3c. As soon as the relay coil isenergized, the switch S8a (FIG. 15) is closed to actuate the bendinghead motor 88 and open the limit switch LS6 to de-energize the relaycoil R11, permitting the switch S11a to open. As soon as the `bendinghead is in its extended position, the limit switch LS7 is closed toenergize the relay coil R10 through the switches S9b and LS7. Theholding switch 810e` is also closed, as is the switch S10a to enable thecircuit through the relay coil R3 for completion by closure of theswitch S11a. As soon as the relay coil R10 s energized, the switch S10bopens to de-energize the relay coil R8 and open the switch SSa therebyetfecting a hydraulic return of the bending head to close the limitswitch LS6 and complete the circuit through the relay R3 by closing theswitch S11a to restart the template drive. As soon as the pin 184 thatinitially tripped the limit switch LS1 moves, the limit switch LS1 isrestored to its original condition.

If either of the limit switch switches LS3 or LS4 are tripped toenergize the relay coils R12 or R13 to cycle either an overbend or anunderbend, respectively, the valve 240` is moved by either of thesolenoids SOL-4 or SOL-5 to rotate the bending head quill stop disc 126accordingly. Since the switches Sltld and S10@ will be closed at altimes except when the relay coil is energized by movement of the bendinghead to its extended position, the circuits through the relay coils R12and R13 are disabled when the bending head is in its extended position.Also it will be noted that the limit switches LS10 and LS11, whichindicate either can overbend or an underbend respectively, must beclosed after actuation or energization of either of the relay coils R12or R13 in order for the relay coil R8 to be energized and effect abending cycle.

Closure of the limit switch LSS by a pin 184 on the cam template 22 willcomplete a circuit through the relay coil R14 closing the switch S14 todisengage the wire feed by retraction of the piston of the motor 182 andthe pressure roll 178. The retraction of the wire drive will close thelimit switch LS12 to enable the template drive motor relay R3. In thismanner, the drive can be disengaged while enabling continued rotation ofthe template drive to trip, for example, the limit switch LS2 to effecta cutotf cycle at the end of a spring forming operation. Should it bedesired to establish template rotation manually to cut the wire ordisengage the wire feed, the push buttons FB2, PB3 and PB4 may be used.Also, it will be noted that when both limit switches LS2 and LSS aretripped simultaneously, the relay coil R14 will remain inactive, byopening the switch S6c, and wire feed will not be interrupted.

In order to understand the manner in which the apparatus describedoperates in practice, reference will be had to an example of a typicalundulating or zig-zag spring which is shown in FIG. 17 of the drawings.Such springs comprise a series of laterally extending torsion bars 244connected alternately on opposite sides by bending bars 246. Also itwill be noted that the undulations established by the torsion bars andlbending bars may lie in different planes. In a typical seat cushion,for example, the front and rear portions of the spring are formed havinglengths 248 and 250 which lie in planes intersecting each other at anangle. Thus, in the spring shown in FIG. 17 the length 248 isestablished at one end by a loop for connection to a frame havingclosely spaced bends a and b. Further bends c, d, e and f serve tocomplete the length 248. The length 250 is begun by a bend g in a planemaking approximately a right angle with respect to the plane establishedby bends a-f. The section or length 250 is then completed in the springshown by bends h, i and j. The primary cushion support portion of thespring begins with a bend k and continues with subsequent bends, each ofwhich may depart slightly from the plane of the preceding bend toestablish the arcuate configuration required by the seat cushion design.

From the description of the wire bending machine illustrated in FIGS. 1to 14 of the drawings, and the circuit diagrams of FIGS. l5 and 16, itwill be apparent to those skilled in the art that the particular shapeof the spring to )e formed, such as the one illustrated in FIG. 17, ispredi- :ated on the shape of the peripheral cam 112 and the rrrangementof timing pins 184 on the programming tern- Jlate 22. In light of thisfeature, and as above mentioned, )y stocking a series of differentlyarranged programming :am templates 22, it is necessary only to selectthe proper lemplate for a particular shape of the spring to be formed.

When the desired cam template 22 has been mounted on :he hub 156 (FIG.14), and assuming the wire W to be Jositioned as shown in FIG. extendingthrough the aper- Lure 54 in the cutoff pin 52, the spring forming cycleis ,nitiated by pressing the push button PBl, it being assumed furtherthat the pump 226 is running. As described in :onnection with thecircuit diagrams of FIGS. 15 and 16, the limit switches LS1 to LSS willeffect first a cutoff of the wire and then the series of bends, such asthe bends z-k followed by a further cutoff and new cycle, wire feed froma coil or other suitable supply (not shown) occurring between the bendssimultaneously with rotation of the ternplate 22. It is preferred that acontinuous supply of the wire W be used so that as each spring or otherbent material product is completed, the latter is severed from the wireW and the product forming cycle repeated. In this way no additionalhandling of the Wire supply is required for the successive formation ofindividual springs, for example, other than occasional replacing a coilof wire.

The angular positions of the bending head about the axis of the wire Wduring the formation of a spring such as the one illustrated in FIG. 17are depicted by FIGS. 18-22. As a'bove mentioned, this angular positionof the bending head is established by the peripheral cam pattern on thetemplate 22 engaged by the follower 110 in the embodiment describedabove. Hence, and as shown in FIGS. 18 and 21, during the formation ofthe bends a-f the bending head will be positioned so that the roller die40 moves in a generally vertical plane, oscillating approximately 180between successive bends to form the spring section 248. Through theformation of the bends g-j to form the section 250 in a planeapproximately at right angles to the plane of the section 248, the camtemplate moves the bending head to an angular position illustrated inFIG. 19 and to position 180 disposed therefrom in the formation of thesection 250. Similarly, the bend k and successive bends in the springare formed with the bending head at a position approximating thatillustrated in FIG. 20 of the drawings. FIG. 23 illustrates theformation of an underbend of approximately 45 by position such as wouldoccur when the underbend stop 150 is positioned in front of the bendinghead quill 80.

An alternative embodiment of the bending machine of this invention isillustrated in FIGS. 24-26 of the drawings. In these figures, partswhich are identical to parts incorporated in the embodiment describedabove are designated by like reference numerals. The embodiment of FIGS.24-26 differs from the embodiment of FIGS. 1-16 principally in thecontrol means for establishing the angular position of the bending headabout the axis of the wire W and in the control of the stroke of thebending head motor 88 and thus of the bending head quill 80. In thislatter respect, the embodiment of FIGS. 24-26 enables an infinitevariation in bending head stroke whereas the embodiment of FIGS. 1-16,as described, is limited to three stroke length positions established bythe stops 150, 152 and 154.

Both of the aforementioned position control functions in the alternativeembodiment are effected electronically by the use of linear variabledifferential transformers available commercially from SchaevitzEngineering, Pennsauken, NJ. These devices are disclosed in a SchaevitzEngineering Technical Bulletin A27 so that further detailed descriptionof these devices, per se, is considered to be unnecessary. In a generalsense, however, the linear variable differential transformers referredto are used in pairs, one transformer of each pair functioning as acontrol transformer whereas the other of each pair is associated withthe device controlled as a feedback transformer. Each of the linearvariable differential transformers includes a core movable in a coil andmay be associated with appropriate electronic circuitry so that acontrol signal is generated when the signal output of the feedbacktransformer corresponds precisely to the signal of the controltransformer, the latter having been positioned either manually ormechanically by a programming device.

As shown in FIG. 24, a programming cam template 22 having a pair ofaxially offset peripheral cam surfaces 252 and 254 is substituted forthe programming cam template 22 in the previously described embodiment.The peripheral cam surface 252 operates to program the respectiveangular positions to which the bending head 14 is moved during anautomatic bending cycle. To effect this control, a cam Ifollower 256 isprovided on one arm 257 of a pivoted bell crank 258. The other arm 260of the bell crank lever is slidably and pivotally connected to a rod 262suitably supported from the machine frame 10 by a bracket 263 forreciprocal movement. A compression spring 264 biases the rod to theright as shown in FIG. 24, thereby to insure contact of the followerroll 256 at all times with the peripheral cam surface 252. The end ofthe rod 262 abuts the end of a plunger 265 directly connected to thecore (not shown) of a linear variable differential transformer 266 ofthe type aforementioned.

As shown in FIGS. 25 and 26, the pinion 122 formed on the shaftextension 94 and described above with respect to FIG. 3b is in thisinstance engaged by a rack 267 slidably mounted in the housing 16 forreciprocation by hydraulic piston-cylinder motor 268. The end of therack 267 projecting from the housing 16 opposite from the motor 268 ispivotally and slidably connected to a lever arm 270 pivotally suspendedfrom a bracket 272 mounted on a linear bearing 274 in turn supported onthe top of the housing 16. A rod 276, slidably received in the bearing244, is also pivotally and slidably connected to the lever arm 270 andabuts at one end against a plunger 278 of another linear variabledifferential transformer 280.

The linear transformer 266 actuated by the cam follower 256 willtherefore function as a control transformer whereas the lineartransformer 280 will function as the feedback transformer in theconventional manner of using such devices as described above. As shownspecifically in FIG. 25, both transformers 266 and 280 are connectedelectrically to a control servo X. Since the details of the controlservo are conventional, further discussion thereof is unnecessary exceptto point out that the control servo X operates to convert the electricalsignals developed by the linear transformers 266 and 280 to a hydrauliccontrol for the hydraulic motor 268. Thus, it will be appreciated thatthe signal variation transmitted from the linear transformer 266 willoperate the motor 268 to advance the rack 267 either to the left or tothe right until the proper position of the rack is reached and indicatedby the feedback linear transformer 280. At this point, the actuation ofthe motor 268 will terminate with the bending head 14 in the angularposition to which the pinion 122 is moved by the rack 266.

The arrangement for controlling the arc through which the bending die 40moves, or the single plane bend angle effected bythe stroke of thebending head motor 88, in the embodiment of FIGS. 24-26, is similar tothe control for the head angle described in the preceding paragraphs. Inthis instance, the peripheral cam surface 254 is engaged by a camfollower 282 mounted on a short arm 284 of a pivoted bell crank 286 asshown in FIG. 24. The other arm 288 of the bell crank 286 is connectedto an axially slidable rod 290 supported in a bracket 292. The rod 290will, therefore, `be positioned by the bell crank 286 in accordance withthe shape of the peripheral cam surface 254. Manual means 293 isprovided by which the axial position of the rod 290 may be controlled byan

